Air motor



Sept. 13, 1966 an VEDDER ETAL 3272M AIR MOTOR Filed Jan. 4, 1965 wzzzzz0 6E? 5 J /WV V5005? ATTORNEY United States Patent 3,272,081 AIR MOTORBorgert Vedder, Fulierton, Calif, and John Vedder, Torrance, Calif.(both of 14032 S. Avalon Blvd, Los Angeles, Calif. 90061) Filed Jan. 4,1965, Ser. No. 422,907 6 Claims. (Cl. 91-228) This invention relates toan air motor for causing a member to reciprocate, for example, thehydraulic piston or ram of a pump.

An object of the invention is to provide a reciprocating air motor thatoperates on the simple and eflicient principle of power magnificationthrough the use of differential piston areas.

Another object of the invention is to provide an air motor embodying anovel form of valving that reverses air flow with each reciprocativemovement in a smooth and eflicient manner.

A further object of the invention is to provide an air motor thatoperates efliciently at high unit pressures of air and with positivenessof opreation due to eflicient sealing between moving parts to minimizeinternal leakage. This feature insures that the motor components movefully and positively in the operation.

This invention also has for its objects to provide such means that arepositive in operation, convenient in use, easily installed in a workingposition and easily disconnected therefrom, economical of manufacture,relatively simple, and of general superiority and serviceability.

The above objects are realized in an air motor that comprises a bodywith an air inlet and an air exhaust, and provided with a set of portsthat are variously connected to said inlet and exhaust and to a passageleading to the upper end of an air cylinder and constituting operatingair pressure against the upper face of an air piston in said cylinder,said ports opening into an axial bore in said body; a four-way valvesleeve movable in said bore between upper and lower positions with aspring to bias the same to its lower position when the air pressurethere on is balanced; a pilot valve guided in said sleeve and providedwith a piston at one end, said pilot valve being shiftable by airpressure controlled by the four-way valve sleeve; a check valve carriedby the pilot valve that opens to the pressure of air flow in theinterior of the pilot valve to provide operating air pressure againstthe under face of said air piston in the air cylinder; a cylindricalstem on the air piston in which the piston on the pilot valve is guided;and sealing means between the body and the stem to provide sealingtherebetween to insure full operative movement by air of the four-wayvalve between upper and lower positions.

The invention also comprises novel details of construction and novelcombinations and arrangements of parts, which will more fully appear inthe course of the following description and which is based on theaccompanying drawing. However, said drawing merely shows, and thefollowing description merely describes, one embodiment of the presentinvention, which given by way of illustration or example only.

In the drawing, like reference characters designate similar parts in theseveral views.

FIG. 1 is a quarter-section view of the present air motor with the partsthereof in the position to direct compressed air against the undersurface of the air piston, the other quarter-section portion being thesame except that the air inlet and exhaust are omitted.

FIG. 2 is a similar view of said air motor with the parts thereof in theposition to direct compressed air against the upper surface of said airpiston.

The present air motor is provided with a body 5 that has an air inletport 6 that leads to a manifold 7, an

air exhaust port 3 that leads to a manifold 9, and one or more airpassages 11), leading from a manifold 11 and opening into the upper endof an air cylinder 12 extending from the lower end of the body 5. Saidbody 5 has a small bore 13 in its upper end with a compressible bumper14 at the upper end of the bore, an O-ring seal 15 being providedadjacent the lower end of said bore. A counterbore 16, provided with abumper 17, extends from the lower end of the small bore 13.

A larger counterbore extension .18 of the counterbore 16 has the bumper18 at its upper end, a still larger counterbore 19 extending from thecounterbore 18, the three manifolds 7, 9 and 11 opening on the bore 19.A bearing 20 is fitted into a counterbore extension 21 at the lower endof the body 5, a sealing O-ring 22 in the body sealing the fit. A bumper23 is provided in the upper face of said bearing 20 which has an innerbore 24 in which an O-ring 25 is fitted.

A liner 26 is fitted into the counterbore 19 between the bearing 21) andthe shoulder that is formed between the latter counterbore and the bore.18 from which it extends. Said liner is provided with lowerlongitudinally spaced ports 27 that connect the manifold 7 with theinner bore of said liner, with upper longitudinally spaced ports 28 thatconnect the manifold 9 with said liner bore, and with intermediate ports29 that connect the manifold 9 with said liner bore.

A four-way slide valve 30, in the form of a tubular portion 31, has asliding fit in the bore of the liner 26, with its upper end 32 engagedwith the bumper 17 when the valve 30 is in raised position, as in FIG.1, and with its lower end 33 engaged with the bumper 23 in the upperface of the bearing 21?, when said head is in lowered position, as inFIG. 2. An inner flange wall 34, provided with an O-ring 35 in the boreof said wall extends from the tubular portion 31 of the head 30. Ports36 are provided in the part of the portion 31 that extends above theflange wall 34. An annular external groove 37 has operative associationwith the ports 27 and 28 to communicate the same, according to theraised and lowered positions of the head, with the ports 29. It will benoted that the bore 30 and the bore of the flange wall 34 are the samediameter. A spring 38 between said flange wall 34 and an abutment wallformed by bores 13 and 16, biases the valve 30 to its lower position.

A pilot valve 39 has a sliding fit in the mentioned bore 30 and the boreof the flange wall 34, the same having an axial bore 41 that is closedat the top and is provided with two sets of radial ports 41 and 42 thatpass air from within the four-way valve 30 to the bore 41). The lowerend of pilot valve 39 comprises a piston 43, a skirt 44 below saidpiston being provided with radial ports 45.

The valve 39, in its bore 40, fixedly mounts a valve seat 46 againstwhich a spring 47 biases a valve body 43 which has angular ports 49 inits Wall as well as a set of longitudinal passages 50. Said latter portsand passages are open to the bore 411 of the valve 39, the former beingclosed when the body 48 is seated on seat 46, and the latter beingclosed by a check valve 51 which opens only in a downward directionunder pressure of air in the valve passage 40.

An air piston 52 has sliding operative engagement in the cylinder 12which is of larger size than the largest bore in the body 5, the samebeing fitted with an O-ring 5 3 to seat against the cylinder. Saidpiston carries an axially disposed ram 54 of considerably smaller sizethan the piston, said ram, due to its smaller size, having a power orpressure factor on its operative end that is the same as the total airpressure on either side of the piston.

The air piston 52 is provided with an upwardly directed stem 55 thatcomprises a tubular extension that has sliding fit in the bore 24 ofbearing and an inner surface that constitutes a cylinder for the piston43. A ported inwardly directed flange 56 at the upper end of said stem55 overstands the piston 43, an O-ring 57 forming a bumper between saidflange and said piston. An O-ring 58 on the upper end of said stem 55 isarranged to seal against the bore 24 of the bearing 20 when the piston52 is at the end of its down stroke. Ports 59 open on a relieved portionof the outer surface of the stem 55.

The ram 54 is provided at its upper end with an enlargement 60 that isconnected to a lower extension of the air piston 52. The upper portionof said enlargement is provided with a bumper pad 61 which is adapted tobe abutted by the lower skirt end 44 of the valve 39. Above saidenlargement, the air piston is provided with passages 62 that open fromthe inner cylinder bore 63 in which the piston 43 of said valve 39operates and into which the radial ports 45 open.

Operation At the end of the down stroke of the ram 54, the four-wayvalve is in the raised position of FIG. 1. Compressed air at inlet 6will pass through the lower of the ports 27 of liner 26 and enter thebore of the valve 30. This air, through ports 41 and 42, enters the boreof the pilot valve 3 9, creating an upward force against the blind endof the bore 40 that raises the valve 39 and divides into a downward airflow that passes through ports in the valve body 48 and opens the checkvalve 51, said air then entering the bore 63 and passing throughpassages 62 to create a force in the direction of arrow 64 between thebottom of the cylinder 12 and the under surface of the air piston 52.

As a result of such air flow, the valve 39 will move upwardly while theair piston 52 is moving through its up stroke. During this up stroke ofthe air piston, the same displaces air in the upper end of the cylinder;this air, by way of passages 10, port 29, groove 37, and the lower ports28, exhausts through the port 8.

It will be noted that the valve 39 cannot move up faster than the piston52 due to the interengagement of the piston 43 of said valve and theflange 56. This insures that the valve 39 cannot prematurely reach itsfourway valve-reversing position. This interengagement, however, allowsthe piston 52 to make its full upward recovery movement to the positionof FIG. 2 before the valve reaches its maximum raised position againstthe bumper 14, as shown. In practice, said valve 39 need not raise tosuch maximum position, but only enough so that the ports 42 thereof passthe O-ring 35 of the distributor head 30 so that the air pressure in thebore 40 can enter the counterbore 16 of the body 5. Since, by the timethe ports 42 pass O-ring 35, the upper end of the valve 39 has enteredthe bore 13 and is sealed by O-ring 15, the pressures in saidcounterbore 16 and in the inside of the air distributor 30 below theflange 34, are equalized. As a consequence, the spring 38 becomeseflective to move the four-Way valve downward to the position of FIG. 2.

In this position, compressed air at inlet 6 will pass through the upperof the ports 27, groove 37, and passages 10, and enters the upper end ofthe cylinder 12 to produce a force on the piston 52, according to arrow65, to move the latter downward in its power stroke. This down stroke ofthe piston 52 causes displacement of air in the cylinder 12 below saidpiston, this air passing through ports 62 into bore 63, unseating thevalve body 48 and passing through angular ports 49 into the bore 40 ofthe valve 39. This air passes through ports 41 when the same becomeuncovered due to the downward movement of the tubular extension and itsflange 56 of the piston 52, into the interior bore of the four-way valve30. At the same time, air from bore 40 will pass through ports 42 intocounterbores 16 and 18 and will exhaust through the upper of ports 28through the exhaust port 8. Upon such exhaust taking place, the pressurewithin the four-way valve 30 will become effective to shift the latterupwardly to the position of FIG. 1, terminating the down or power strokeand completing the cycle of operation.

Due to the sliding fit among the valves 30 and 31, the liner 26, thestem 55 and the piston 52 in the cylinder 12, the fit between thebearing 20 and the stem 55 is quite loose. When the annular clearance atthat point is added to the small ports 59 and the ports in the flange56, the air-passing area between the interior of the fourway valve andthe upper port of the air cylinder is large.

Under low air pressure of between five and twenty pounds, the pressurein the interior of valve 30 leaks to the air cylinder 12 too rapidly forthe air inlet through the lower of the ports 27, as the same is beinguncovered, to complete the full up movement of the valve 30. The lattermay hang in an intermediate position resulting in a constant bypass ofair around the bearing 20. The O-ring 58 is provided to prevent suchbypass of air, since the same closes the annular clearance between saidbearing and the piston stem 55, leaving only the small ports 59 andthose in the flange 56 to exhaust the interior of the four-way valve.Hence, the four-way valve will shift fully to its maximum opening of thelower of the ports 27.

It is this feature that enables the present air motor to operate withcompressed air as low as five psi. and as high as one hundred p.s.i., ormore.

While the foregoing has illustrated and described what is nowcontemplated to be the best mode of carrying out the invention, theconstruction is, of course, subject to modirfication without departingfrom the spirit and scope of the invention. Therefore, it is not desiredto restrict the invention to the particular form of constructionillustrated and described, but to cover all modifications that may fallwithin the scope of the appended claims.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. An air motor comprising:

(a) a body with an air inlet and an air exhaust and having a bore andtwo sets of ports connecting said bore and the inlet and exhaust,respectively,

(b) an air cylinder extending from said body and open to said bore,

(0) the body having ports intermediate the mentioned two sets of portsand passage means from said intermediate ports to the portion of thecylinder adjacent the body,

((1) an air piston in said cylinder provided with a hollow stemoperative in the body bore and having ports opening through the bottomthereof,

(e) a four-way valve sleeve movable in said bore between upper and lowerpositions with a spring to bias the sleeve to its lower position, saidsleeve in one position providing communication between the air inlet andthe body bore and between the air exhaust, through the passage means,and the upper portion of the air cylinder, and said sleeve in the otherposition providing communication between the air inlet and said passagemeans and upper portion of the air cylinder, and between the air exhaustand the body bore,

(f) a pilot valve having an axial bore and guided in said sleeveprovided with a piston at one end, said pilot valve being shiftable byair pressure from the inlet entering the body bore, as controlled by thefour-way valve sleeve,

(g) a check valve, carried by the pilot valve, that opens to airpressure in the bore thereof to provide operating pressure, through theports in the air piston, on the under surface of the latter, and

(h) a second check valve carried by the pilot valve that opens in theopposite direction to pass pressure air from beneath the air piston intothe body bore.

2. An air motor according to claim 1 in which the fourway valve sleeveis provided with a flange in guiding and sealing engagement with thepilot valve, ports being provided in said valve opening the axial boreof the latter to the body bore in one position of the valve, said portsproviding pressure-balanced air on opposite sides of said flange, thementioned spring shifting the four-way valve sleeve to said otherposition during such air-balanced condition of pressure in the valvebore.

3. An air motor according to claim 2 in which the fourway valve sleeveis provided with portions formed to open the ports in the body that aredirectly connected to the exhaust of the body, when said sleeve isshifted by said spring.

4. An air motor comprising:

(a) a body with an air inlet and an air exhaust and having a bore andtwo sets of ports connecting said bore and the inlet and exhaust,respectively,

(b) an air cylinder extending from said body and open to said bore,

(c) the body having ports intermediate the mentioned two sets of portsand passage means from said intermediate ports to the portion of thecylinder adjacent the body,

(d) an air piston in said cylinder provided with a hollow stem operativein the body bore and having ports opening through the bottom thereof,

(e) a four-way valve sleeve movable in said bore between upper and lowerpositions with a spring to bias the sleeve to its lower position, saidsleeve in one position providing communication between the air inlet andthe body bore and between the air exhaust, through the passage means,and the upper portion of the air cylinder, and said sleeve in the otherposition providing communication between the air inlet and said passagemeans and upper portion of the air cylinder, and between the air exhaustand the body bore,

(f) a pilot valve having an axial bore and guided in said sleeveprovided with a piston at one end, said pilot valve being shiftable byair pressure from the inlet entering the body bore, as controlled by thefour-way valve sleeve,

(g) a check valve, carried by the pilot valve, that opens to airpressure in the bore thereof to provide operating pressure, through theports in the air piston, on the under surface of the latter,

(h) a second check valve carried by the pilot valve that opens in theopposite direction to pass pressure air from beneath the air piston intothe body bore,

(i) a bearing provided in the body and having a bore concentric with andsmaller than the body bore, the air piston stern extending through saidbearing bore, and

(j) means carried by the piston stem to seal against said bearing borewhen the air piston is projected from the body bore.

5. An air motor comprising:

(a) a body with an air inlet and an air exhaust and having a bore andtwo sets of ports connecting said bore and the inlet and exhaust,respectively,

(b) an air cylinder extending from said body and open to said bore,

(0) the body having ports intermediate the mentioned two sets of portsand passage means from said intermediate ports to the portion of thecylinder adjacent the body,

(d) an air piston in said cylinder provided with a hollow sternoperative in the body bore and having ports opening through the bottomthereof,

(e) a four-way valve sleeve movable in said bore between upper and lowerpositions with a spring to bias the sleeve to its lower position, saidsleeve in one position providing communication between the air inlet andthe body bore and between the air exhaust, through the passage means,and the upper portion of the air cylinder, and said sleeve in the otherposition providing communication between the air inlet and said passagemeans and upper portion of the air cylinder, and between the air exhaustand the body bore,

(f) a pilot valve having an axial bore and guided in said sleeveprovided with a piston at one end, said pilot valve being shiftable byair pressure from the inlet entering the body bore, as controlled by thefour-way valve sleeve,

(g) a check valve, carried by the pilot valve, that opens to airpressure in the bore thereof to provide operating pressure, through theports in the air piston, on the under surface of the latter,

(h) a second check valve carried by the pilot valve that opens in theopposite direction to pass pressure air from beneath the air piston intothe body bore,

(i) the air piston stem having ports therein that open the bore of thebody to the air cylinder above the air piston,

(j) a bearing provided in the body at the lower end thereof and havingan axial bore concentric with and smaller than the body bore, the airpiston stem extending loosely through said bearing bore, and

(k) means carried by the piston stem to seal against said bearing borewhen the air piston is projected from the body bore.

6. An air motor according to claim 5 in which the latter means comprisesa sealing ring that closes air flow through said loose fit between thebearing bore and stem to lessen the air flow from the body bore to theair cylinder above the air piston and retaining such pressure in thebody bore as to insure full shift of the four-way valve sleeve.

References Cited by the Examiner UNITED STATES PATENTS 2,296,647 9/1942McCormick 91-308 2,361,757 10/1944 Fink 91-313 3,171,809 3/1965 Cox91222 MARTIN P. SCHWADRON, Primary Examiner.

P. E. MASLOUSKY, Assistant Examiner.

1. AN AIR MOTOR COMPRISING: (A) A BODY WITH AN AIR INLET AND AN AIREXHAUST AND HAVING A BORE AND TWO SETS OF PORTS CONNECTING SAID BORE ANDTHE INLET AND EXHAUST, RESPECTIVELY, (B) AN AIR CYLINDER EXTENDING FROMSAID BODY AND OPEN TO SAID BORE, (C) THE BODY HAVING PORTS INTERMEDIATETHE MENTIONED TWO SETS OF PORTS AND PASSAGE MEANS FROM SAID INTERMEDIATEPORTS TO THE PORTION OF THE CYLINDER ADJACENT THE BODY, (D) AN AIRPISTON IN SAID CYLINDER PROVIDED WITH A HOLLOW STEM OPERATIVE IN THEBODY BORE AND HAVING PORTS OPENING THROUGH THE BOTTOM THEREOF, (E) AFOUR-WAY VALVE SLEEVE MOVABLE IN SAID BORE BETWEEN UPPER AND LOWERPOSITIONS WITH A SPRING TO BIAS THE SLEEVE TO ITS LOWER POSITION, SAIDSLEEVE IN ONE POSITION PROVIDING COMMUNICATION BETWEEN THE AIR INLET ANDTHE BODY BORE AND BETWEEN THE AIR EXHAUST, THROUGH THE PASSAGE MEANS,AND THE UPPER PORTION OF THE AIR CYLINDER, AND SAID SLEEVE IN THE OTHERPOSITION PROVIDING COMMUNICATION BETWEEN THE AIR INLET AND SAID PASSAGEMEANS AND UPPER PORTION OF THE AIR CYLINDER, AND BETWEEN THE AIR EXHAUSTAND THE BODY BORE, (F) A PILOT VALVE HAVING AN AXIAL BORE AND GUIDED INSAID SLEEVE PROVIDED WITH A PISTON AT ONE END, SAID PILOT VALVE BEINGSHIFTABLE BY AIR PRESSURE FROM THE INLET ENTERING THE BODY BORE, ASCONTROLLED BY THE FOUR-WAY VALVE SLEEVE, (G) A CHECK VALVE, CARRIED BYTHE PILOT VALVE, THAT OPENS TO AIR PRESSURE IN THE BORE THEREOF TOPROVIDE OPERATING PRESSURE, THROUGH THE PORTS IN THE AIR PISTON, ON THEUNDER SURFACE OF THE LATTER, AND (H) A SECOND CHECK VALVE CARRIED BY THEPILOT VALVE THAT OPENS IN THE OPPOSITE DIRECTION TO PASS PRESSURE AIRFROM BENEATH THE AIR PISTON INTO THE BODY BORE.